Understanding Loudness, Why the Fuss about LUFS – AP108

In this session I take a look at measuring and normalising to a LUFS value in Reaper.
The first part of the episode covers what LUFS actually represents and how it is calculated. I start with discussing what Peak and RMS represent and how they are measured and the issues with normalising to each of these values when applied to Loudness.

In short LUFS is calculated by taking the RMS, through a EQ filter that approximates the bias of human hearing and gates out any quiet content, or non foreground content, from the calculation. It is an attempt to put a reproducible value or measure on Loudness, which is inherently subjective. At this time it is the best way of doing this.

I look at two dialogs available in Reaper thanks to the SWS Extension. The first is a tool to normalise either Items or Tracks to an LUFS value. This dialog is not currently bound in the OSARA key map and I have bound it to Shift+U. Normalize loudness of selected items/tracks.
The LUFS analysis dialog available in the Extensions menu or with an action I have bound to Command+Shift+U is also covered. I discuss the various data it provides including the Integrated, Range, True Peak, Short-term, and Momentary values.

I look at some White and Pink noise examples as well as some more real world values when analysing a track from a podcast. The potential issues of simply normalising a file without considering the overall dynamic range of the file is discussed. One limitation of using the analysis tool on a track is that it does not take into account any dynamic compression or effects placed on the track. However if you place the effects on an item and than measure the track, the impact of the effects will be calculated in the values.